1. Field of the Invention
The present invention relates generally to a liquid storage container. More particularly, the present invention relates to a liquid storage container for storing a liquid usable as a recording agent for a recording apparatus such as an ink jet recording apparatus, a photoelectrical copying machine, a facsimile unit or the like. In addition, the present invention relates to a recording unit integrally including a liquid storing container of the foregoing type. Additionally, the present invention relates to a recording apparatus having a recording unit of the foregoing type mounted thereon. Further, the present invention relates to a method of filling a liquid storage container of the foregoing type with liquid from the outside.
2. Description of Related Art
A conventional liquid injection recording apparatus (hereinafter referred to as an ink jet recording apparatus) is generally constructed such that a recording head for discharging ink therefrom and an ink storing section associated with the recording head are separately-arranged as individual components at different positions located away from each other but they are operatively connected to each other via an ink feeding system inclusive of an ink feeding pipe interposed therebetween.
Because of a necessity for extending a long ink feeding pipe between both the components, the conventional ink jet recording apparatus constructed in the above-described manner has problems that a piping operation is achieved for the apparatus with much difficulties, and moreover, vaporized ink or air is liable to invade in the apparatus. To cope with the foregoing problems, the assignee common to the present invention proposed an ink jet recording apparatus of the type that an recording head and an ink storing section are united with each other in the form of an integral unit (cartridge), as disclosed in official gazettes of Japanese Patent Application Laying-open Nos. 61-249757, 63-22653 and 2-192954. According to the proposals, the aforementioned problems associated with evaporation of ink and invasion of air can be obviated, and an advantage attainable from the proposals is that any unskilled-user can easily handle an ink feeding system including an ink storing section because no piping operation is required.
However, when ink in the ink jet recording apparatus is completely consumed, a user should purchase a new cartridge having a recording head and an ink tank cartridge integrated with each other so as to allow the used ink cartridge to be exchanged with a new one. In practice, there often arises an occasion that ink in the cartridge is completely consumed but the recording head is unavoidably exchanged with a new one although it has still some running life. In the circumstances as mentioned above, many requests have been raised from users for providing an ink jet recording apparatus which assures that a recording head including highly functional components such as piezo-electric elements, silicon wafers or the like can fully and effectively be utilized.
To satisfactorily meet these requests, the assignee proposed an on-carriage type ink jet recording apparatus including a recording head and an ink tank cartridge integrated with each other without any necessity for performing a piping operation wherein the recording head can fully be utilized over its entire running life, and moreover, the recording head can be disconnected from the ink tank cartridge when the latter is exchanged with a new one. With this on-carriage type ink jet recording apparatus constructed in that way, an empty ink tank cartridge can repeatedly be exchanged with a new one until the recording head reaches the end of its running life. As long as ordinary documents are printed with the ink jet recording apparatus, a series of recording operation can sequentially be performed for several thousand sheets of paper with a single recording head while only the empty ink tank cartridge is repeatedly exchanged with a new one. With the on-carriage type ink jet recording apparatus, when any recording operation can not be performed any more because the running life of the recording head expires, a user is required to purchase a new recording head so that a recording operation can be restarted with the new recording head. In addition, the assignee made various kinds of proposals with respect to an ink storing container to be integrated with a recording head in practical use.
As a printing technique, hardware and software for personal computers advance year by year in the aforementioned circumstances, it becomes possible to perform each printing operation with greater ease and a more beautiful appearance. On the other hand, the performance required from a recording apparatus is elevated with improved versatility. Although there often arises the question as to whether a dye based ink should be used or a pigment based ink should be used, each of these inks has its own features. This makes it difficult to finally determine the type of ink to be selected. In other words, a user is required to make a decision at his discretion as to which type of ink to be used. This tendency is remarkably intensified at present because users increasingly employ color printing. In addition, it is expected that various types of inks each having different physical and chemical properties are put in practical use. This fact has a significant effect on designing of an ink tank cartridge. Thus, there arises a necessity for preparing an ink tank cartridge corresponding to each type of ink to be used.
Another problem is concerned with an optimal working volume of ink tank cartridge which should be determined corresponding to a certain kind of ink. For example, in the case that a user frequently performs recording operations, it is desirable for him or her to print many sheets of paper with the reduced number of exchanging operations each performed for exchanging an empty ink tank cartridge with a new one. On the contrary, when a user prints a small number of sheets every time a recording operation is performed by him or her, it is economically unacceptable for the following reason to use an ink tank cartridge containing a large quantity of ink. Specifically, when the recording head is kept inoperative for a long time after a small quantity of ink is consumed for each recording operation, volatile components contained in ink are vaporized therefrom, causing coloring substances to be adversely transformed. For this reason, a user is required to exchange the ink tank cartridge with a new one every time a recording operation is performed. This leads to the result that he or she is spending money for the unused ink remaining in the enchanged ink tank cartridge. In the circumstances as mentioned above, many requests have been raised from many users for providing an ink tank cartridge which is simple in structure and contains a small quantity of ink. On the other hand, for a user who prints a large number of sheets at every recording operation, there is a need of preparing an ink tank cartridge containing a possibly large quantity of ink in the restrictively predetermined working volume thereof. In this case, it is desirable that each recording operation is achieved at a low printing cost although the ink tank cartridge is produced at an expensive cost. This shows merely an example of explaining the current tendency that it is expected that various types of advanced techniques will be developed with respect to the ink jet recording apparatus in future. In addition, it is anticipated that each ink tank cartridge is constructed with a different structure corresponding to a common recording head.
In the case that an exchangeable type ink tank cartridge is used for the ink jet recording apparatus, it is necessary that measure be taken for the purpose of preventing dust or similar foreign materials from entering the ink jet recording head when a porous ink absorbing member molded of an elastic material is employed as means for retaining ink in the ink tank cartridge. In practice, however, since fine fractures are torn or peeled away from the porous ink absorbing member during each recording operation, it is additionally necessary that a filtering member is disposed in an ink flow path in order to prevent the fine fractures from entering the recording head. To this end, the filter may be disposed on the ink tank side. In this case, a filter should be disposed on every ink tank cartridge. This is because if a filter is disposed only the recording head side, there arises a malfunction in that dust or similar foreign materials are deposited on the filter, causing the latter to be clogged with the dust or the like before the running life of the recording head expires.
To assure that the ink jet recording apparatus is designed with smaller dimensions, it is obviously required that the ink tank cartridge itself is designed with smaller dimensions. To this end, the working volume of the ink tank cartridge should restrictively be determined. However, since a quantity of ink to be consumed by the recording head corresponding to a predetermined content of recording is kept constant regardless of the dimensions of the ink jet recording apparatus, it is required that a running cost of the ink tank cartridge is taken into account for the purpose of designing each ink tank cartridge with smaller dimensions on the assumption that the ink tank cartridge containing no ink is exchanged with a new one. To meet the requirement, it is highly requested that an utilization efficiency of the ink stored in the ink tank cartridge be increased as high as possible.
However, to satisfy the foregoing request, the ink jet recording apparatus has the following problems to be solved. Specifically, to improve reliability of each recording operation, air (bubbles) accumulated in the recording head as time elapses or introduced in an ink flow path when the ink tank cartridge is exchanged with a new one should be removed from the ink. To this end, a pump arranged in the ink jet recording apparatus is driven to removably suck the air together with the ink discharged from ink discharging orifices. An extra quantity of ink sucked together with the air with the aid of the pump is wasted as it cannot be used for recording. In the case of a conventional comparatively large-sized ink jet recording apparatus, since an ink tank cartridge has a certain allowance in respect to an ink storing capacity, when a power source of the ink jet recording apparatus is turned on, a pump is automatically driven once per 72 hours so as to increase reliability of each recording operation. In addition, when the ink jet recording apparatus is designed with sufficient allowance in respect of a capacity of sucking ink per each pumping operation as well as an ink sucking pressure induced by the pump, air bubbles can reliably be removed from the recording head and the ink tank cartridge in the ink jet recording apparatus.
However, in the case of a small-sized ink tank cartridge having a small ink storing capacity, when a large quantity of ink is wasted by performing the same pumping operation as mentioned above, a frequency of repeatedly exchanging each ink tank cartridge containing no ink with a new one is increased, causing a user to endure a troublesome exchanging operation accompanied by an increased running cost. Thus, the advantageous effect attained by designing each ink tank cartridge with smaller dimensions is reduced or lost. To cope with the foregoing problem, a proposal was made as to a process of minimizing a quantity of ink to be uselessly pumped out together with air bubbles per each pumping operation.
To assure that an ink tank cartridge can be disconnected from a recording head on a printer carriage, it is inevitably necessary to dispose a valve mechanism in the ink tank cartridge in order to prevent ink from leaking from the ink tank cartridge by quickly sealably closing an ink flow path with the valve mechanism after the ink tank cartridge is disconnected from the recording head. In addition, a filter is disposed in the recording head on the downstream side of the valve mechanism. The volume between the ink storing section and the filter is called a valve space. When the ink tank cartridge and the recording head are connected to and disconnected from each other several times for some reason, there arise malfunctions that air bubbles enter the valve space, resulting in each recording operation being unstably achieved after the ink tank cartridge is connected to the recording head. Moreover, ink feeding is interrupted due to the invasion of the air bubbles in the course of certain recording operations. To obviate the foregoing malfunctions, it suffices that the pump is driven in the same manner as the conventional ink jet recording apparatus. However, when the quantity of ink that is wasted each pumping operation is restrictively reduced for the small-sized ink jet recording apparatus in the above-described manner, there arises a problem as noted below.
The foregoing problem will be described below with reference to FIGS. 3A to 3C and FIGS. 4A to 4C. For example, when an ink tank cartridge 2-1 and an ink jet recording head 2-2 are frequently connected to and disconnected from each other or when an assembly of the ink tank cartridge 2-1 and the ink jet recording head 202 is kept inoperative for a long time of several months, a large part of the ink held in the space defined between the ink jet recording head 2-2 and a valve space 2-3 is lost due to vaporization of the ink. In this case, ink can not satisfactorily be fed to the ink jet recording head 2-2 merely by a single pumping operation achieved by a pump 2-4 having a predetermined flow rate case as mentioned above. In such a case it is necessary to continuously perform the same pumping operations several times in order to compensate for the shortage of pumping capacity.
As is apparent from FIGS. 3A to 3C, in the case that the pumping operations are intermittently performed several times, the ink 2-5 once sucked in the ink jet recording head 2-2 in the course of each pumping operation is caused to return to an ink reservoir 2-7. To prevent an occurrence of ink return flow as mentioned above, it is recommended that adequate means for preventing the ink 2-5 from reversely flowing to the ink reservoir 2-7, e.g., a cap 2-6 for retaining the ink pressure in the valve space 2-3, as shown in FIGS. 4A to 4C, is continuously brought in close contact with the ink jet recording head 2-2 during a series of pumping operations. However, the arrangement of the cap 2-6 with high reliability maintained during the pumping operations prevents the ink jet recording apparatus from being designed with smaller dimensions. In addition, another problem is that the ink jet recording apparatus is fabricated at an increased cost.
For example, when a porous member is received in an ink tank cartridge as disclosed in an Japanese Patent Publication No. 3-41351, it is necessary that a filter is brought in close contact with the porous member. However, in the case of an ink jet recording unit of the type including an ink jet recording head and an ink tank cartridge disconnectable from each other, when a user erroneously repeatedly connects a single ink tank cartridge to the opposing ink jet recording head and disconnects the former from the latter, the porous member received in the ink tank cartridge is adversely transformed, resulting in the filter disposed in the ink jet recording head failing to come in close contact with the porous member. Thus, there is a possibility that ink can not correctly be fed to the ink jet recording head. In addition, in the case that air bubbles enter in the ink tank cartridge, there is a possibility that the air bubbles enter an ink feeding path during a certain recording operation, causing droplets of ink to be incorrectly discharged from ink discharging orifices.
In view of the fact that a large quantity of ink remains in the porous member without any feeding of the ink to the ink jet recording head, many proposals were made in order to obviate the foregoing malfunction. Among the proposals, one proposal is such that a quantity of projecting of a projection from the recording head side toward the porous member is restrictively determined so as to allow the projection to properly come in contact with the porous member. Another proposal is such that a plurality of ribs are caused to extend along the inner wall surface of the ink tank cartridge in order to distribute the atmospheric air introduced into the ink tank cartridge via an atmospheric air intake port over the surface of the porous member.
Although the above-mentioned proposals are certainly effective for coping with various kinds of requests raised from many users status more that ink jet recording apparatuses are increasingly put into practical use, it has been clarified by the invertors that a mutual relationship among components each constituting an ink jet recording apparatus serving as a printer unit is not hitherto recognized as an unstable factor but has an unexpected technical significance.
Especially, in the case that the ink jet recording apparatus serving as a printer unit is integrally installed in information processing equipment such as a personal computer or the like so that the whole information processing equipment is constructed with smaller dimensions, the real recognition of the foregoing mutual relationship is effectively useful for fabrication the ink jet recording apparatus.